“…At present, ethanol fermentation technology generally employs batch bioreactor systems and only occasionally continues reactors where the cells are freely suspended in the liquid phase (Choi et al, 2009;Hong et al, 2009;Zhang et al, 2009;Turhan et al, 2010;Ghorbani et al, 2011;Li et al, 2010;Tang et al, 2010) in recent years, many workers have used immobilized-cell systems to ferment a wide variety of carbohydrates to ethanol (Liu et al, 2009;Singh et al, 2009;Pacheco et al, 2010;Ghorbani et al, 2011;Pruksathorn and Vitidsant, 2009) reported that certain strains of S. cerveisiae can undergo up to 10 fermentation cycles using molasses-containing medium. Alshiyab et al (2009) reported that by using bigger reactor size, the effect of gaseous products in fermentation medium was reduced and enhanced both bacterial productivity and biomass concentration, where Brethauer and Wyman (2010) reported that some continuous fermentations are now employed for commercial ethanol production from cane sugar and corn to take advantage of higher volumetric productivity, reduced labor costs, and reduced vessel down time for cleaning and filling.…”